os: Implement os::Event

[Nitr4m12]

The class itself is similar to os::Mutex, in that it's mostly a wrapper around global functions, so this follows a similar structure to #78.

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This change is 

[MonsterDruide1]

@MonsterDruide1 reviewed 4 files and all commit messages, and made 5 comments.
Reviewable status: all files reviewed, 6 unresolved discussions (waiting on Nitr4m12 and Pistonight).

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a discussion (no related file):
add new files to CMakeLists.txt

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include/nn/os/os_Event.h line 47 at r2 (raw file):

};

}  // namespace nn::os

add newline at end of file

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include/nn/os/os_EventCommon.h line 4 at r2 (raw file):

namespace nn::os {
enum EventClearMode { EventClearMode_ManualClear, EventClearMode_AutoClear };

or does this cause issues with symbols/compiling somewhere?

Suggestion:

enum class EventClearMode { ManualClear, AutoClear };

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include/nn/os/os_EventCommon.h line 5 at r2 (raw file):

namespace nn::os {
enum EventClearMode { EventClearMode_ManualClear, EventClearMode_AutoClear };
}  // namespace nn::os

add newline at end of file

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include/nn/os/os_EventTypes.h line 26 at r2 (raw file):

static_assert(std::is_trivial<EventType>::value, "EventType non trivial");

}  // namespace nn::os

add newline at end of file

[Nitr4m12]

@Nitr4m12 reviewed 5 files and all commit messages, and made 5 comments.
Reviewable status: 1 of 5 files reviewed, 6 unresolved discussions (waiting on MonsterDruide1 and Pistonight).

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a discussion (no related file):

Previously, MonsterDruide1 wrote…

add new files to CMakeLists.txt

Done

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include/nn/os/os_Event.h line 47 at r2 (raw file):

Previously, MonsterDruide1 wrote…

add newline at end of file

Done

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include/nn/os/os_EventCommon.h line 4 at r2 (raw file):

Previously, MonsterDruide1 wrote…

or does this cause issues with symbols/compiling somewhere?

This causes issues when compiling sead

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include/nn/os/os_EventCommon.h line 5 at r2 (raw file):

Previously, MonsterDruide1 wrote…

add newline at end of file

Done

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include/nn/os/os_EventTypes.h line 26 at r2 (raw file):

Previously, MonsterDruide1 wrote…

add newline at end of file

Done

[MonsterDruide1]

@MonsterDruide1 reviewed 4 files and all commit messages, and resolved 5 discussions.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on Pistonight).